Communication device, relay device, control method, and computer-readable storage medium

ABSTRACT

A communication device that performs communication wirelessly transmits, to one or more other communication devices, a request signal requesting information indicating a condition regarding communication with a predetermined device, in each of one or more communication methods in the one or more other communication devices, receives, from at least any of the one or more other communication devices, a response including the information indicating the condition regarding the communication in the other communication devices, selects, based on the received response, a device to be requested to transfer the communication of the communication device from a transmission source device of the response, and selects a communication method in the device to be used for transferring, and performs connection establishment processing including requesting the selected device to relay the communication of the communication device.

CROSS-REFERENCE TO RELATED APPLICATION(S)

This application is a continuation of International Patent ApplicationNo. PCT/JP2021/006982 filed on Feb. 25, 2021, the entire disclosures ofwhich is incorporated herein by reference.

BACKGROUND OF THE INVENTION Field of the Invention

The present invention relates to a communication device, a relay device,a control method, and a program, and more particularly, to a techniquefor selecting a relay device in relay transmission.

Description of the Related Art

Vehicle-to-Everything (V2X) communication, by which a vehiclecommunicates wirelessly with another vehicle or an object, enables thevehicle to acquire various types of information or to provideinformation to others. When a vehicle transmits data to a device such asa server on the Internet or a network that has been constructed by aservice provider, the vehicle has to connect to a predeterminedcommunication device such as, for example, a base station or an accesspoint through which the vehicle is capable of connecting to the network.However, vehicles are not always in an environment where the connectionto such a predetermined communication device is enabled. For thisreason, it is supposed that a vehicle communicates with a predeterminedcommunication device through, for example, another vehicle capable ofconnecting to such a predetermined communication device. Japanese PatentLaid-Open No. 2017-184051 describes a configuration for connectingbetween vehicles to transfer data to a predetermined node. In JapanesePatent Laid-Open No. 2017-184051, a vehicle close to the predeterminednode is identified by communication between the vehicles, and data istransferred to the vehicle close to the predetermined node.

When a communication device establishes a connection with another devicein order to communicate with a predetermined device, it is supposed thatthe communication device is incapable of recognizing what type ofcommunication such another device is capable of performing with thepredetermined device. In this case, after the communication device isconnected with another device, the connection between such anotherdevice and the predetermined device can be established only in acommunication method at an insufficient communication rate. Hence, thecommunication device may be incapable of communicating with thepredetermined device at a sufficient communication rate.

SUMMARY OF THE INVENTION

The present invention provides a technique that enables a communicationdevice to appropriately select another device that relays communicationwith a predetermined device.

A communication device according to one aspect of the present inventionis a communication device that performs communication wirelessly, thecommunication device comprising: a requesting unit configured totransmit, to one or more other communication devices, a request signalrequesting information indicating a condition regarding communicationbetween a predetermined device and the other communication devices, ineach of one or more communication methods in the one or more othercommunication devices, the predetermined device being different from thecommunication device; a receiving unit configured to receive, from atleast any of the one or more other communication devices, a responseincluding the information indicating the condition regarding thecommunication in the other communication devices; a selecting unitconfigured to select, based on the response received by the receivingunit, a device to be requested to transfer the communication of thecommunication device from a transmission source device of the response,and to select a communication method to be used for transferring, in thedevice; and a performing unit configured to perform connectionestablishment processing including requesting the device selected by theselecting unit to relay the communication of the communication device,by performing communication between the device and the predetermineddevice using the communication method selected by the selecting unit.

A relay device according to one aspect of the present invention is arelay device that relays communication wirelessly between acommunication device and a predetermined device, the relay devicecomprising: a receiving unit configured to receive, from thecommunication device, a request signal requesting information indicatinga condition regarding communication with the predetermined device ineach of one or more communication methods in the relay device; and atransmitting unit configured to transmit, to the communication device, aresponse including the information indicating the condition regardingthe communication in the relay device.

Further features of the present invention will become apparent from thefollowing description of exemplary embodiments with reference to theattached drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are incorporated in and constitute apart of the specification, illustrate embodiments of the invention and,together with the description, serve to explain principles of theinvention.

FIG. 1 is a diagram illustrating a system configuration example.

FIG. 2 is a diagram illustrating a hardware configuration example of acommunication device.

FIG. 3 is a diagram illustrating a functional configuration example ofthe communication device that requests for relaying.

FIG. 4 is a diagram illustrating a functional configuration example ofthe communication device that enables relaying.

FIG. 5 is a diagram illustrating an example of a flow of processingperformed in the system.

DESCRIPTION OF THE EMBODIMENTS

Hereinafter, embodiments will be described in detail with reference tothe attached drawings. Note, the following embodiments are not intendedto limit the scope of the claimed invention, and limitation is not madeto an invention that requires a combination of all features described inthe embodiments. Two or more of the multiple features described in theembodiments may be combined as appropriate. Furthermore, the samereference numerals are given to the same or similar configurations, andredundant description thereof is omitted.

(System Configuration)

FIG. 1 illustrates a configuration example of a system in the presentembodiment. The present system is a wireless communication system inwhich vehicles 111 to 114, which are capable of performing wirelesscommunication, connect to a predetermined network such as the Internet,and perform communication. The vehicles 111 to 114 according to thepresent embodiment connect to a base station 101 of a cellularcommunication system, for example, and perform communication with apredetermined communication device. In addition, the vehicles 111 to 114are, for example, configured to be capable of communicating with eachother by connecting to each other in a communication method differentfrom the cellular communication method for communicating with the basestation 101. Here, the communication method different from the cellularcommunication method is, for example, any communication method ofcellular Vehicle-to-Everything (V2X), wireless LAN, Dedicated ShortRange Communications (DSRC), and Bluetooth (registered trademark). Notethat although the cellular V2X is one aspect of the cellularcommunication method, it is not used for the communication between thebase station and the terminal (that is, the vehicle 111 to the vehicle114), but is used for the communication between a device other than thebase station and the terminal (the vehicle 111 to the vehicle 114).Therefore, these communication methods are treated as differentcommunication methods throughout the present embodiment and the scope ofclaims. Note that a combination of the cellular communication method andany other communication method is an example, and the vehicles 111 to114 are configured to connect to a first device such as the base station101 in a first communication method, and to be connectable with eachother in a second communication method different from the firstcommunication method. Note that in FIG. 1 , only one base station 101and four vehicles 111 to 114 are illustrated, but it is needless to saythat a large number of these devices can be present.

By using the second communication method, the vehicles 111 to 114 arecapable of performing, for example, not only vehicle-to-vehiclecommunication but also communication with another device such as, forexample, an access point of a wireless LAN. In one example, it isassumed that the vehicle 112 is present in a location where it ispossible to communicate with a predetermined device 121, which is fixedin a communication method other than the cellular communication method,and is in a state in which it is possible to communicate with thepredetermined device 121 through a wireless LAN. Note that the vehicle112 is connectable to communicate with further another device other thanthe predetermined device 121 in a communication method such as awireless LAN or Bluetooth. In addition, the vehicle 113 and the vehicle114 are also connectable to communicate with one or more other devicesin the surroundings by using a communication method corresponding toeach device, depending on the location. Note that FIG. 1 illustrates anexample in which the vehicle 112 is directly connectable to thepredetermined device 121, which is fixed, but there is no intention ofbeing limited to this. For example, the vehicle 112 may be capable ofcommunicating with the predetermined device 121, which is fixed, througha wireless communication device such as further another vehicle. Thesame applies to other vehicles.

By performing cellular communication with the base station 101, thevehicles 111 to 114 are capable of transmitting, for example,information that has been acquired by sensors of the respective vehiclesto a device such as a predetermined information processing server. Theinformation processing server is capable of performing various types ofprocessing such as control for automated driving with this information.In addition, by performing the cellular communication with the basestation 101, the vehicles 111 to 114 are capable of acquiring varioustypes of information such as driving control information and serviceinformation in accordance with the locations of the vehicles from aserver that holds, for example, predetermined information. On the otherhand, in an environment in which a large number of vehicles communicatein parallel, the communication capacity that can be provided by the basestation 101 may be insufficient. For this reason, in the presentembodiment, for example, the communication of the vehicle 111 isoffloaded onto another device through the other vehicles 112 to 114.Note that the communication of the vehicle 112 to the vehicle 114 can besimilarly offloaded through another vehicle. However, here, adescription will be given by focusing on offloading the communication ofthe vehicle 111.

The vehicle 111 establishes a connection with a vehicle in thesurroundings, and communicates with a predetermined device such as aserver on the Internet through the connection. For this purpose, thevehicle 111 transmits a connection request for requesting anothervehicle in the surroundings to relay the communication, and establishesa connection. At this time, the vehicle 111 can, for example, establisha connection with another vehicle having good wireless quality ofcommunication with the vehicle 111 in the second communication method.In one example, the vehicle 111 can establish a connection with thevehicle 112 in the second communication method to cause the vehicle 112to transfer the communication of the self-device. In this situation, thevehicle 112 is capable of using, for example, a plurality ofcommunication methods, and the communication performance can be greatlychanged depending on which communication method the vehicle 112 uses.For example, there can be a communication method in which an achievablemaximum communication rate is insufficient to transfer communication ofthe vehicle 111. In addition, in a case where a communication method inwhich the achievable maximum communication rate is sufficiently large isused, but in a state in which communication in such a communicationmethod is congested, the communication of the vehicle 111 cannot betransferred by using such a communication method.

In the present embodiment, in consideration of such circumstances, acommunication device (for example, the vehicle 111) transmits a requestsignal for requesting one or more other communication devices capable ofrelaying the communication of the self-device, for informationindicating a condition regarding communication with a predeterminedcommunication device in each of one or more communication methods insuch one or more other communication devices (for example, the vehicle112 to the vehicle 114). Note that the predetermined communicationdevice is, for example, a wireless communication device (for example,the predetermined device 121) capable of accessing a device thatterminates communication such as the Internet, and a differentpredetermined communication device can be set for every communicationmethod. Upon receiving the request signal, another communication devicetransmits, to the communication device, a response including theinformation indicating the condition regarding the communication withthe predetermined communication device with regard to at least any (insome cases, each of all available communication methods) of thecommunication methods available to the self-device. The communicationdevice receives the response from at least any of the one or more othercommunication devices, selects a device (that is, a relay device) to berequested to transfer the communication of the communication deviceitself, from the one or more other communication devices (in oneexample, another communication device that is a transmission source ofthe response), based on the response, and selects a communication methodthat should be used for the transfer in the device that has beenselected. Then, the communication device performs connectionestablishment processing including requesting the device that has beenselected to relay the communication of the communication device usingthe communication method that has been selected.

In this manner, in the present embodiment, the communication deviceacquires, from the other communication devices to be candidates eachhaving a possibility that the relay is requested, whether it is possibleto communicate in each of the one or more communication methodsavailable to the other communication devices and information of acommunication capacity about whether a sufficient communication capacityis obtainable through the communication. Then, the communication devicedesignates a communication method between another communication deviceand a predetermined communication device, and requests for relaying thecommunication, so that a communication device suitable for relaying thecommunication of the self-device connects to the predeterminedcommunication device in a communication method suitable for thecommunication device to relay the communication of the self-device.According to this, it is possible to prevent degradation in theperformance of communication between the communication device and thepredetermined communication device, resulting from the communicationbetween another communication device and the predetermined communicationdevice.

Note that in one example, the request signal is transmitted in abroadcast manner, and is simultaneously transmitted to othercommunication devices in the surroundings of the communication device.Accordingly, the communication device is capable of completinginformation collection from other communication devices in a shortperiod of time. In addition, the request signal may include informationindicating requesting for relaying the communication of thecommunication device. Note that only the information indicatingrequesting for relaying the communication of the communication devicemay be transmitted to other communication devices. That is, theinformation explicitly indicating that the information of the conditionregarding the communication in every communication method is requesteddoes not have to be included in the request signal, and the informationindicating requesting for relaying the communication may implicitlyindicate that the information of the condition regarding thecommunication in every communication method is requested.

In one example, the communication method includes at least one of acellular communication method, a wireless LAN communication method, anda Bluetooth communication method. Note that in addition to or instead ofthese methods, any other communication method may be used. Note that inthe present embodiment, the cellular communication method is availableto both the vehicle 111 that requests the relay transmission and thevehicle 112 to the vehicle 114, which can be requested for the relaytransmission. However, it is supposed that, for example, the wirelessquality of the cellular communication method in the vehicle 112 to thevehicle 114 is sufficiently better than that in the vehicle 111, and itis possible to significantly reduce the resource usage amount by causingthe vehicle 112 to the vehicle 114 to relay the communication of thevehicle 111 rather than the vehicle 111 directly communicating with thebase station 101. For this reason, also with regard to the cellularcommunication method available to the vehicle 111, the vehicle 112 tothe vehicle 114 can transmit information indicating the conditionregarding such a communication method to the vehicle 111.

Note that in requesting for the information of the condition regardingthe communication, the communication device may transmit a requestsignal that designates a communication method to be reported as theinformation. In this case, with regard to the designated communicationmethod, another communication device transmits, to the communicationdevice, a response including the information indicating the conditionregarding the communication with the predetermined communication devicethat is an offload target in the designated communication method.According to this, for example, in view of the communication methodstandards, it is possible to prevent reporting on the information abouta communication method that is incapable of satisfying the communicationperformance requested by the communication device, and waste of wirelessresources can be prevented. In addition, the communication device maydesignate information indicating the communication performance requestedby the communication of the self-device, in the request signal. In thiscase, with regard to the communication method that satisfies thedesignated communication performance, another communication devicetransmits, to the communication device, information indicating thecondition regarding the communication with the predeterminedcommunication device that is the offload target in the communicationmethod. Note that in this case, another communication device does notreport, for example, a communication method in which no device that isan offload target is present in the surroundings or a communicationmethod for which it has been determined that satisfying the requestedcommunication performance is not possible, based on the wirelessquality. In one example, another communication device does not transmita response, in a case where it is not possible to satisfy the requestedcommunication performance in any of the communication methods availableto the self-device. Note that another communication device may transmit,to the communication device, a response including information indicatingwhether the requested communication performance is satisfied, withregard to each of one or more communication methods. According to this,since another communication device reports information only about thecommunication method capable of satisfying the communication performancerequested by the communication device, it becomes possible to preventwaste of wireless resources.

In one example, the information of the condition regarding thecommunication in a certain communication method includes informationabout the wireless quality with a predetermined communication device inanother communication device, in a case where such a communicationmethod is used. The wireless quality can include, for example, receivedsignal strength, a signal to noise ratio (SNR), a signal to interferenceplus noise ratio (SINR), reference signal received power (RSRP), orreference signal received quality (RSRQ) in such another communicationdevice. Accordingly, the communication device becomes capable ofselecting a communication method having sufficiently good wirelessquality as a communication method that should be used by anothercommunication device for a relay target.

In addition, in one example, the information of the condition regardingthe communication in a certain communication method can includeinformation indicating whether another communication device has alreadyestablished a connection using such a communication method. According tothis, the communication device is capable of identifying, for example,another communication device having a communication method in which theconnection has been already established, as a device capable of promptlyrelaying the communication of the self-device. Therefore, for example,in a case where the communication device performs the communication thatshould be promptly relayed, it is possible to determine to request acommunication device having the communication method in which such aconnection has been established to relay the communication in such acommunication method.

In addition, the information of the condition regarding thecommunication in a certain communication method may include informationindicating a congestion state (congestion degree) of the communicationin such a communication method. According to this, by trying not toselect the communication method in the congestion state (congested), thecommunication device becomes capable of selecting another communicationdevice capable of stably relaying the communication of the self-deviceand the communication method that should be used.

Note that the communication device can wait for a response from each ofthe other communication devices over a predetermined period, and canselect a device to be requested to transfer the communication and acommunication method that should be used in transferring by such adevice, based on the response that has been received during thepredetermined period. Accordingly, the communication device is capableof appropriately selecting a device suitable for relaying thecommunication from the other communication devices in the surroundingsof the self-device.

In addition, in a case where the communication device receives aresponse including information indicating the communication methodcapable of satisfying the communication performance that should besatisfied in relaying the communication of the self-device, thecommunication device can select a transmission source device of theresponse that has been received, as a device to be requested to transferthe communication, without waiting for receiving a response from anotherdevice, and can select the communication method indicated in theresponse that it is possible to satisfy the communication performance,as a communication method that should be used. According to this, withina short period of time, after confirming that another communicationdevice suitable for relaying is present, it becomes possible to performthe connection establishment processing with such another communicationdevice. Therefore, it becomes possible to promptly start thecommunication between the communication device and the predeterminedcommunication device.

Note that, for example, in a case where there is no predeterminedcommunication device that can be an offload target of the communicationof the communication device, another communication device can try not totransmit the report. According to this, the communication device cantreat only the other communication devices that are transmission sourcesof the responses as candidates for the relay device, and can select adevice to be requested to relay the communication for implementationfrom them.

Hereinafter, configurations and operations of the vehicle 111 to thevehicle 114 that perform such processing will be described. Note that inthe present embodiment, the processing to be performed by the vehicle111 to the vehicle 114 is described. However, the “vehicle” is merelyone aspect of a communication device, and the discussion in the presentembodiment is applicable to a wireless communication device in anyaspect.

(Device Configuration)

FIG. 2 illustrates a hardware configuration example of the communicationdevice mounted on the vehicle 111 to the vehicle 114 in the presentembodiment. The communication device includes a general-purpose computerin one example, and the computer includes, for example, a CPU 201, amemory 202, a storage device 203, a communication circuit 204, and aninput and output circuit 205. Note that FIG. 2 illustrates aconfiguration example of hardware according to the present embodiment,and illustrations of the other configurations are omitted. The CPU 201is, for example, a central processing unit (CPU) that performsprocessing to be described later and that controls the entire device, byexecuting a program stored in the memory 202. Note that the CPU 201 canbe substituted by any one or more processors such as a micro processingunit (MPU) or an application-specific integrated circuit (ASIC). Thememory 202 holds a program for causing the communication device toperform various types of processing, and functions as a work memory atthe time of executing the program. In one example, the memory 202 is arandom access memory (RAM) or a read-only memory (ROM). The storagedevice 203 is, for example, a detachable external storage device, abuilt-in hard disk drive, or the like, and holds various types ofinformation. The communication circuit 204 performs signal processingrelated to communication, acquires various types of information from anexternal device through a communication network, and transmits thevarious types of information to the external device. Note that theinformation that has been acquired by the communication circuit 204 canbe stored in, for example, the memory 202 or the storage device 203.Note that the communication device can include a plurality ofcommunication circuits 204. The input and output circuit 205 controls,for example, outputs of screen information to be displayed on a displaydevice, not illustrated, audio information to be output from a speaker,and receiving of user inputs via a keyboard, a pointing device, or thelike. Note that the input and output circuit 205 may control a devicethat integrally inputs into and outputs from a touch panel or the like.Note that the configuration of FIG. 2 is an example, and for example,the communication device may include dedicated hardware for performingthe above-described processing.

FIG. 3 illustrates a functional configuration example of a communicationdevice that requests for relaying communication. Note that out of thevehicle 111 to the vehicle 114, in the present embodiment, thedescription is given with regard to a case where the vehicle 111 is acommunication device that requests for relaying the communication.However, the vehicle 112 to the vehicle 114 can also operate as acommunication device that requests for relaying the communication, andthus can have functions as illustrated in FIG. 3 . The communicationdevice includes, for example, an information request unit 301, aninformation reception unit 302, a selection unit 303, and a connectionestablishment processing unit 304, as its functions. Note that thesefunctional units may be implemented, for example, by the CPU 201executing a program stored in the memory 202 or the storage device 203,or may be implemented by dedicated hardware. Note that since thedetailed operations of the respective functional units have beendescribed above, only the functions are outlined here, and the detaileddescriptions are omitted.

The information request unit 301 transmits, to one or more othercommunication devices, a request signal for requesting informationindicating a condition regarding communication between the one or moreother communication devices and a predetermined communication device ineach of one or more communication methods. As a response to the requestsignal that has been transmitted by the information request unit 301,the information reception unit 302 receives, from at least any of theone or more other communication devices, the information indicating thecondition regarding the communication in each of the one or morecommunication methods, in such a device. The selection unit 303 selectsa device to be requested to transfer the communication of theself-device, for example, from the other communication devices that aretransmission sources of responses, based on the information that hasbeen received, and further selects a communication method that should beused with a predetermined communication device to transfer thecommunication of the communication device, in such a device. Theconnection establishment processing unit 304 performs connectionestablishment processing including requesting the device that has beenselected by the selection unit 303 to perform communication between sucha device and the predetermined communication device using thecommunication method that has been selected by the selection unit 303 soas to relay the communication of the communication device. That is, theconnection establishment processing unit 304 also makes a requestrelated to the communication between another communication device andthe predetermined communication device, while performing the connectionestablishment processing between the communication device and anothercommunication device.

FIG. 4 illustrates a functional configuration example of a communicationdevice that receives a request for relaying the communication and thatoperates as a relay device. Note that out of the vehicle 111 to thevehicle 114, in the present embodiment, the description is given withregard to a case where the vehicle 112 to the vehicle 114 arecommunication devices each of which operates as a relay device. However,the vehicle 111 is also capable of operating as a communication devicethat operates as the relay device, and thus can have functions asillustrated in FIG. 4 . The communication device includes, for example,a request reception unit 401, an information providing unit 402, and arelay processing unit 403, as its functions. Note that these functionalunits may be implemented, for example, by the CPU 201 executing aprogram stored in the memory 202 or the storage device 203, or may beimplemented by dedicated hardware. Note that since the detailedoperations of the respective functional units have been described above,only the functions are outlined here, and the detailed descriptions areomitted.

The request reception unit 401 receives a request signal requestinginformation indicating a condition regarding the communication betweenthe communication device and a predetermined communication device ineach of one or more communication methods, from other communicationdevices in the surroundings. Note that the request signal may be asignal indicating requesting for relaying the communication of atransmission source device, and can be a signal in any format having ameaning of requesting information indicating a condition regarding thecommunication in each of one or more communication methods between adevice that has received the signal and a predetermined communicationdevice. In response to receiving the request signal, the informationproviding unit 402 transmits a response including the informationindicating the condition regarding the communication with thepredetermined communication device in each of one or more communicationmethods in the self-device. The relay processing unit 403 receives asignal including information of requesting for relaying thecommunication of a device from the device that has received the aboveresponse, the signal designating a communication method that should beused in the communication with the predetermined communication device.Then, the relay processing unit 403 establishes a connection with atransmission source device of the signal, and conducts control so as torelay the communication between the transmission source device of thesignal and the predetermined communication device, by using thecommunication with a predetermined communication device in thecommunication method that has been designated. Note that the relayprocessing unit 403 establishes a connection with the device that is thetransmission source device of the above-described signal, by using, forexample, the communication method used when the request signal that hasbeen received by the request reception unit 401 was transmitted.

(Flow of Processing)

Next, an example of a flow of processing performed by theabove-described communication system will be described. Here, it isassumed that the vehicle 111 selects the vehicle 112 from the vehicle112 to the vehicle 114, as the relay device, and a communication methodused with the predetermined device 121 is designated as a communicationmethod that should be used by the vehicle 112. Note that details of eachprocess to be described later have been described above. Therefore, inthe description here, only the flow of the processing is outlined, andthe detailed description is not repeated. The present processing isimplemented by, for example, the CPU 201 executing a program stored inthe memory 202 or the storage device 203.

In the present system, first, the vehicle 111 transmits, to each thevehicle 112 to the vehicle 114, a request signal for requestinginformation indicating a condition regarding communication between sucha vehicle and a predetermined device that enables communication with adevice (for example, a server on the Internet) to be a communicationpartner of the vehicle 111, in each of one or more communication methodsavailable to such a vehicle (S501). Upon receiving this request signal,the vehicle 112 to the vehicle 114 each identify a communicationcondition with a predetermined device capable of reaching thecommunication partner of the vehicle 111, with regard to each of thecommunication methods available to the self-device, and transmits aresponse including the information regarding the communication conditionto the vehicle 111 (S502). Note that, for example, in a case where thevehicle 112 to the vehicle 114 cannot find a predetermined devicecapable of reaching the communication partner of the vehicle 111 in anycommunication methods, the response of S502 does not have to betransmitted. For example, FIG. 5 illustrates an example in which thevehicle 114 does not transmit the response. Thereafter, the vehicle 111selects a device that relays the communication of the self-device and acommunication method that should be used in such a device, based on thereceived information (S503). Note that, for example, in a case where thevehicle 111 receives the response from a vehicle capable ofcommunicating with a predetermined device in a communication method bywhich it is possible to obtain the communication performance requestedin the communication of the self-device, the vehicle 111 may select thevehicle that is a transmission source of the response as the relaydevice, without waiting for receiving the response from another vehicle.Here, as described above, it is assumed that the vehicle 111 selects thevehicle 112 as the relay device, and selects one communication method(for example, a wireless LAN communication method) capable ofcommunicating with the predetermined device 121, as a communicationmethod that should be used by the vehicle 112.

In response to the selection, the vehicle 111 transmits a relay requestthat designates the selected communication method to the vehicle 112(S504). Upon receiving this relay request, the vehicle 112 establishes aconnection with the vehicle 111 (S505). Here, it is assumed that thevehicle 112 establishes the connection with the vehicle 111, by using,for example, the communication method in which the signal of S501 hasbeen transmitted and received, and in the connection establishmentprocessing, a procedure defined in the communication standards of thecommunication method is performed. In addition, the vehicle 112establishes a connection with the predetermined device 121 in thecommunication method designated in the relay request (S506). Note thatin a case where the vehicle 112 has already established the connectionwith the predetermined device 121, the processing of S506 may beomitted.

Note that the vehicle 112 identifies the communication condition in eachcommunication method, when providing the information in S502, but canestablish a connection with a partner device at the time of identifyingthe communication condition in the designated communication method. Thatis, in the present embodiment, it is assumed that the vehicle 112identified the condition regarding the communication with thepredetermined device 121 with regard to a certain communication method,and transmitted the identified information to the vehicle 111 in S502.Note that, for example, when transmitting the information indicating thecondition regarding the communication in each communication method tothe vehicle 111, the vehicle 112 to the vehicle 114 may also notifyinformation indicating the partner device at the time of identifying thecondition regarding the communication. In this case, the vehicle 111 maynotify the relay device (the vehicle 112) that has been selected ofinformation indicating the predetermined communication device that is aconnection target. In this situation, the vehicle 111 may also notify ofthe communication method that should be used, or may only notify of thecommunication method to be implicitly used by indicating the informationof the connection target, and does not have to explicitly notify of thecommunication method that should be used.

After both the connection with the vehicle 111 and the connection withthe predetermined device 121 are established, the vehicle 112 startsrelaying the communication of the vehicle 111 (S507).

In this manner, the vehicle 111 selects another vehicle (the vehicle112) capable of relaying the communication of the self-device withsufficient quality, and further identifies, in such another vehicle thathas been selected, a communication method that should be used in thecommunication to a predetermined communication device (the predetermineddevice 121) as a relay target. Accordingly, the device that has beenselected as the relay device relays in the communication method capableof achieving the communication performance requested in thecommunication of the vehicle 111, so that the vehicle 111 becomescapable of communicating with sufficient communication performance.

Summary of Embodiments

-   -   1. A communication device according to the embodiment above is:    -   a communication device that performs communication wirelessly,        the communication device comprising:    -   a requesting unit configured to transmit, to one or more other        communication devices, a request signal requesting information        indicating a condition regarding communication between a        predetermined device and the other communication devices, in        each of one or more communication methods in the one or more        other communication devices, the predetermined device being        different from the communication device;    -   a receiving unit configured to receive, from at least any of the        one or more other communication devices, a response including        the information indicating the condition regarding the        communication in the other communication devices;    -   a selecting unit configured to select, based on the response        received by the receiving unit, a device to be requested to        transfer the communication of the communication device from a        transmission source device of the response, and to select a        communication method to be used for transferring, in the device;        and    -   a performing unit configured to perform connection establishment        processing including requesting the device selected by the        selecting unit to relay the communication of the communication        device, by performing communication between the device and the        predetermined device using the communication method selected by        the selecting unit.

According to this embodiment, when the communication device requests theother communication devices to relay the communication with thepredetermined device, the communication device is capable of determininganother communication device that should relay in consideration of thecommunication methods available to each of the other communicationdevices, and is capable of designating a communication method thatshould be used by such another communication device to communicate withthe predetermined device. According to this, out of the communicationmethods available to the other communication devices, it is possible tocause the communication device to use a communication method suitablefor transferring the communication, so that the communication device cancommunicate with the predetermined device in a good condition.

-   -   2. In the embodiment according to 1 above,    -   the requesting unit designates the one or more communication        methods in the request signal, and requests the one or more        other communication devices for the information indicating the        condition regarding the communication between the other        communication devices and the predetermined device in the        communication method designated.

According to this embodiment, the information about the communicationmethod that should be provided by the other communication devices isdesignated beforehand. Therefore, it is possible to suppress an amountof information that should be notified from the other communicationdevices to the communication device. In one example, transmission andreception of information about a communication method, in whichrequested communication performance is not obtainable even with the bestachievable communication quality, can be omitted.

-   -   3. In the embodiment according to 1 or 2 above,    -   the requesting unit designates, in the request signal,        communication performance requested in the communication of the        communication device, and requests transmission of the        information indicating the condition regarding the communication        with the predetermined device in each of the one or more        communication methods, and    -   the receiving unit receives the response from the other        communication devices capable of communicating with the        predetermined device in a communication method that satisfies        the communication performance.

According to this embodiment, the information that should be providedfor the communication device by the other communication devices islimited to the information about the communication method that cansatisfy the communication performance requested by the communicationdevice. Therefore, the communication amount related to the provision ofthis information can be suppressed.

-   -   4. In the embodiment according to any one of 1 to 3 above,    -   the information indicating the condition regarding the        communication includes information regarding wireless quality        between the other communication devices and the predetermined        device in each of the one or more communication methods.

According to this embodiment, the communication device is capable ofrecognizing which communication method should be used by anothercommunication device to obtain sufficient wireless quality.

-   -   5. In the embodiment according to 4 above,    -   the wireless quality includes received signal strength, a signal        to noise ratio, a signal to interference plus noise ratio,        reference signal received power, or reference signal received        quality in the one or more other communication devices.

According to this embodiment, the communication device is capable ofobjectively recognizing the wireless quality obtained in the othercommunication devices.

-   -   6. In the embodiment according to any one of 1 to 5 above,    -   the information indicating the condition regarding the        communication includes information indicating whether a        connection is established between the other communication        devices and the predetermined device using each of the one or        more communication methods.

According to this embodiment, the communication device is capable ofselecting another communication device that has already established theconnection with the predetermined device and that has high reliabilityof enabling the relay communication, and a communication method thatshould be used.

-   -   7. In the embodiment according to any one of 1 to 6 above,    -   the information indicating the condition regarding the        communication includes information indicating a congestion state        of the communication using each of the one or more communication        methods.

According to this embodiment, it is possible to prevent thecommunication device from selecting another communication device that isincapable of relaying the communication with sufficient quality becauseof congestion, as a device that relays the communication of theself-device.

-   -   8. In the embodiment according to any one of 1 to 7 above,    -   the one or more communication methods include a cellular        communication method, a wireless LAN communication method, or a        Bluetooth communication method.

According to this embodiment, a procedure according to each of theabove-described embodiments is applicable, presupposing a widely usedcommunication method.

-   -   9. In the embodiment according to any one of 1 to 8 above,    -   the receiving unit waits for the response for a predetermined        period of time, and the selecting unit selects the device to be        requested to transfer the communication, based on the response        received during the predetermined period.

According to this embodiment, the communication device is capable ofselecting another communication device that can achieve more appropriatecommunication performance and a communication method that should beused, from responses that have been received within a predeterminedperiod.

-   -   10. In the embodiment according to any one of 1 to 8 above,    -   the selecting unit selects the transmission source device of the        response received as the device to be requested to transfer the        communication, without waiting for receiving the response from        another device, based on receiving the response including the        information indicating the condition regarding the communication        indicating that performance requested in transferring the        communication of the communication device to the predetermined        device is satisfiable.

According to this embodiment, the communication device is capable ofrecognizing that a device that can satisfy the performance requested bythe self-device, and is then capable of requesting such a device torelay the communication in a short period of time.

-   -   11. In the embodiment according to any one of 1 to 10 above,    -   the requesting unit transmits the request signal in a broadcast        manner.

According to this embodiment, it is possible to simultaneously requestinformation from each of the other communication devices present in thesurroundings.

-   -   12. In the embodiment according to any one of 1 to 11 above,    -   the request signal includes information indicating requesting        for relaying the communication of the communication device.

According to this embodiment, for example, by configuring not totransmit a response from another communication device that is incapableof relaying the communication or that rejects relaying the communicationof the communication device, it is possible to prevent the communicationdevice from performing unnecessary processing, such that thecommunication device selects such a device, and after establishes aconnection, the relay is rejected.

-   -   13. In the embodiment according to any one of 1 to 12 above,    -   the communication device is a vehicle.

According to this embodiment, although the other communication devicesin the surroundings change in accordance with movements of vehicles, thecommunication device is capable of appropriately selecting a relaydevice that should perform relay transmission and a communication methodthat should be used by the relay device, regardless of the change.

-   -   14. A relay device according to embodiments above is:    -   a relay device that relays communication wirelessly between a        communication device and a predetermined device, the relay        device comprising:    -   a receiving unit configured to receive, from the communication        device, a request signal requesting information indicating a        condition regarding communication with the predetermined device        in each of one or more communication methods in the relay        device; and    -   a transmitting unit configured to transmit, to the communication        device, a response including the information indicating the        condition regarding the communication in the relay device.

According to this embodiment, by notifying the communication device ofthe communication method and the condition of the communication in acase where a relay device performs communication between thecommunication device and the predetermined device, the communicationdevice is enabled to select a relay device suitable for thecommunication with the predetermined device, and the communicationdevice is enabled to recognize which communication method should be usedby the relay device to enable the relay communication requested by thecommunication device. Accordingly, the communication device becomescapable of selecting a communication method suitable for transferringthe communication of the communication device, from the communicationmethods available to the relay device.

-   -   15. In the embodiment according to 14 above,    -   the request signal includes information designating the one or        more communication methods, and the transmitting unit transmits        the response including the information indicating the condition        regarding the communication with the predetermined device in a        communication method designated.

According to this embodiment, since the information of the communicationmethod that should be provided by the relay device is designatedbeforehand, the amount of information that should be notified from therelay device to the communication device can be suppressed. In oneexample, transmission and reception of information about a communicationmethod, in which requested communication performance is not obtainableeven with the best achievable communication quality, can be omitted.

-   -   16. In the embodiment according to 14 above,    -   the request signal includes information designating        communication performance requested for the communication of the        communication device, and the transmitting unit transmits the        response including the information indicating the condition        regarding the communication with the predetermined device with        regard to a communication method that satisfies the        communication performance.

According to this embodiment, since the information that should beprovided for the communication device by the relay device is limited tothe information of the communication method that can satisfy thecommunication performance requested by the communication device, thecommunication amount related to the provision of this information can besuppressed.

-   -   17. In the embodiment according to any one of 14 to 16 above,    -   the information indicating the condition regarding the        communication includes information regarding wireless quality        with the predetermined device in each of the one or more        communication methods.

According to this embodiment, the communication device is capable ofrecognizing which communication method should be used by the relaydevice to obtain sufficient wireless quality.

-   -   18. In the embodiment according to 17 above,    -   the wireless quality includes received signal strength, a signal        to noise ratio, a signal to interference plus noise ratio,        reference signal received power, or reference signal received        quality, in the relay device.

According to this embodiment, the communication device is capable ofobjectively recognizing the wireless quality obtained in the relaydevice.

-   -   19. In the embodiment according to any one of 14 to 18 above,    -   the information indicating the condition regarding the        communication includes information indicating whether a        connection is established with the predetermined device using        each of the one or more communication methods.

According to this embodiment, the communication device is capable ofselecting a communication method in which the connection has beenalready established between the relay device and the predetermineddevice, and which has high reliability of enabling the relaycommunication.

-   -   20. In the embodiment according to any one of 14 to 19 above,    -   the information indicating the condition regarding the        communication includes information indicating a congestion state        of the communication using each of the one or more communication        methods.

According to this embodiment, it is possible to prevent thecommunication device from selecting another communication device that isincapable of relaying the communication with sufficient quality becauseof congestion.

-   -   21. In the embodiment according to any one of 14 to 20 above,    -   the one or more communication methods include a cellular        communication method, a wireless LAN communication method, or a        Bluetooth communication method.

According to this embodiment, a procedure according to each of theabove-described embodiments is applicable, presupposing a widely usedcommunication method.

-   -   22. In the embodiment according to any one of 14 to 21 above,    -   the relay device is a vehicle.

According to this embodiment, although the communication performance ofevery communication method between a vehicle and a predetermined devicechanges in accordance with a movement of the vehicle, the communicationdevice is capable of appropriately selecting a relay device that shouldperform relay transmission and a communication method that should beused by the relay device, in consideration of the change.

-   -   23. A control method according to the embodiment above is:    -   a control method performed by a communication device that        performs communication wirelessly, the control method        comprising:    -   transmitting, to one or more other communication devices, a        request signal requesting information indicating a condition        regarding communication between a predetermined device and the        other communication devices, in each of one or more        communication methods in the one or more other communication        devices, the predetermined device being different from the        communication device;    -   receiving, from at least any of the one or more other        communication devices, a response including the information        indicating the condition regarding the communication in the        other communication devices;    -   selecting, based on the response received, a device to be        requested to transfer the communication of the communication        device from a transmission source device of the response, and        selecting a communication method to be used for transferring, in        the device; and    -   performing connection establishment processing including        requesting the device selected to relay the communication of the        communication device, by performing communication between the        device and the predetermined device using the communication        method selected.

According to this embodiment, when the communication device requests theother communication devices to relay the communication with thepredetermined device, the communication device is capable of determininganother communication device that should relay in consideration of thecommunication methods available to each of the other communicationdevices, and is capable of designating a communication method thatshould be used by such another communication device to communicate withthe predetermined device. According to this, out of the communicationmethods available to the other communication devices, it is possible tocause the communication device to use a communication method suitablefor transferring the communication, so that the communication device cancommunicate with the predetermined device in a good condition.

-   -   24. A control method according to the embodiment above is:    -   a control method performed by a relay device that relays        communication wirelessly between a communication device and a        predetermined device, the control method comprising:    -   receiving, from the communication device, a request signal        requesting information indicating a condition regarding        communication with the predetermined device in each of one or        more communication methods in the relay device; and    -   transmitting, to the communication device, a response including        the information indicating the condition regarding the        communication in the relay device.

According to this embodiment, by notifying the communication device ofthe communication method and the condition of the communication in acase where a relay device performs communication between thecommunication device and the predetermined device, the communicationdevice is enabled to select a relay device suitable for thecommunication with the predetermined device, and the communicationdevice is enabled to recognize which communication method should be usedby the relay device to enable the relay communication requested by thecommunication device. Accordingly, the communication device becomescapable of selecting a communication method suitable for transferringthe communication of the communication device, from the communicationmethods available to the relay device.

-   -   25. A program according to the embodiment above is:    -   a program for causing a computer included in a communication        device that performs communication wirelessly to:    -   transmit, to one or more other communication devices, a request        signal requesting information indicating a condition regarding        communication between a predetermined device and the other        communication devices, in each of one or more communication        methods in the one or more other communication devices, the        predetermined device being different from the communication        device;    -   receive, from at least any of the one or more other        communication devices, a response including the information        indicating the condition regarding the communication in the        other communication devices;    -   select, based on the response received, a device to be requested        to transfer the communication of the communication device from a        transmission source device of the response, and select a        communication method to be used for transferring, in the device;        and    -   perform connection establishment processing including requesting        the device selected to relay the communication of the        communication device, by performing communication between the        device and the predetermined device using the communication        method selected.

According to this embodiment, when the communication device requests theother communication devices to relay the communication with thepredetermined device, the communication device is capable of determininganother communication device that should relay in consideration of thecommunication methods available to each of the other communicationdevices, and is capable of designating a communication method thatshould be used by such another communication device to communicate withthe predetermined device. According to this, out of the communicationmethods available to the other communication devices, it is possible tocause the communication device to use a communication method suitablefor transferring the communication, so that the communication device cancommunicate with the predetermined device in a good condition.

-   -   26. A program according to the embodiment above is:    -   a program for causing a computer included in a relay device that        relays communication wirelessly between a communication device        and a predetermined device to:    -   receive, from the communication device, a request signal        requesting information indicating a condition regarding        communication with the predetermined device in each of one or        more communication methods in the relay device; and    -   transmit, to the communication device, a response including the        information indicating the condition regarding the communication        in the relay device.

According to this embodiment, by notifying the communication device ofthe communication method and the condition of the communication in acase where a relay device performs communication between thecommunication device and the predetermined device, the communicationdevice is enabled to select a relay device suitable for thecommunication with the predetermined device, and the communicationdevice is enabled to recognize which communication method should be usedby the relay device to enable the relay communication requested by thecommunication device. Accordingly, the communication device becomescapable of selecting a communication method suitable for transferringthe communication of the communication device, from the communicationmethods available to the relay device.

The invention is not limited to the foregoing embodiments, and variousvariations/changes are possible within the spirit of the invention.

What is claimed is:
 1. A communication device that performscommunication wirelessly, the communication device comprising: arequesting unit configured to transmit, to one or more othercommunication devices, a request signal requesting informationindicating a condition regarding communication between a predetermineddevice and the other communication devices, in each of one or morecommunication methods in the one or more other communication devices,the predetermined device being different from the communication device;a receiving unit configured to receive, from at least any of the one ormore other communication devices, a response including the informationindicating the condition regarding the communication in the othercommunication devices; a selecting unit configured to select, based onthe response received by the receiving unit, a device to be requested totransfer the communication of the communication device from atransmission source device of the response, and to select acommunication method to be used for transferring, in the device; and aperforming unit configured to perform connection establishmentprocessing including requesting the device selected by the selectingunit to relay the communication of the communication device, byperforming communication between the device and the predetermined deviceusing the communication method selected by the selecting unit.
 2. Thecommunication device according to claim 1, wherein the requesting unitdesignates the one or more communication methods in the request signal,and requests the one or more other communication devices for theinformation indicating the condition regarding the communication betweenthe other communication devices and the predetermined device in thecommunication method designated.
 3. The communication device accordingto claim 1, wherein the requesting unit designates, in the requestsignal, communication performance requested in the communication of thecommunication device, and requests transmission of the informationindicating the condition regarding the communication with thepredetermined device in each of the one or more communication methods,and the receiving unit receives the response from the othercommunication devices capable of communicating with the predetermineddevice in a communication method that satisfies the communicationperformance.
 4. The communication device according to claim 1, whereinthe information indicating the condition regarding the communicationincludes information regarding wireless quality between the othercommunication devices and the predetermined device in each of the one ormore communication methods.
 5. The communication device according toclaim 4, wherein the wireless quality includes received signal strength,a signal to noise ratio, a signal to interference plus noise ratio,reference signal received power, or reference signal received quality inthe one or more other communication devices.
 6. The communication deviceaccording to claim 1, wherein the information indicating the conditionregarding the communication includes information indicating whether aconnection is established between the other communication devices andthe predetermined device using each of the one or more communicationmethods.
 7. The communication device according to claim 1, wherein theinformation indicating the condition regarding the communicationincludes information indicating a congestion state of the communicationusing each of the one or more communication methods.
 8. Thecommunication device according to claim 1, wherein the one or morecommunication methods include a cellular communication method, awireless LAN communication method, or a Bluetooth communication method.9. The communication device according to claim 1, wherein the receivingunit waits for the response for a predetermined period of time, and theselecting unit selects the device to be requested to transfer thecommunication, based on the response received during the predeterminedperiod.
 10. The communication device according to claim 1, wherein theselecting unit selects the transmission source device of the responsereceived as the device to be requested to transfer the communication,without waiting for receiving the response from another device, based onreceiving the response including the information indicating thecondition regarding the communication indicating that performancerequested in transferring the communication of the communication deviceto the predetermined device is satisfiable.
 11. The communication deviceaccording to claim 1, wherein the requesting unit transmits the requestsignal in a broadcast manner.
 12. The communication device according toclaim 1, wherein the request signal includes information indicatingrequesting for relaying the communication of the communication device.13. The communication device according to claim 1, wherein thecommunication device is a vehicle.
 14. A relay device that relayscommunication wirelessly between a communication device and apredetermined device, the relay device comprising: a receiving unitconfigured to receive, from the communication device, a request signalrequesting information indicating a condition regarding communicationwith the predetermined device in each of one or more communicationmethods in the relay device; and a transmitting unit configured totransmit, to the communication device, a response including theinformation indicating the condition regarding the communication in therelay device.
 15. The relay device according to claim 14, wherein therequest signal includes information designating the one or morecommunication methods, and the transmitting unit transmits the responseincluding the information indicating the condition regarding thecommunication with the predetermined device in a communication methoddesignated.
 16. The relay device according to claim 14, wherein therequest signal includes information designating communicationperformance requested for the communication of the communication device,and the transmitting unit transmits the response including theinformation indicating the condition regarding the communication withthe predetermined device with regard to a communication method thatsatisfies the communication performance.
 17. The relay device accordingto claim 14, wherein the information indicating the condition regardingthe communication includes information regarding wireless quality withthe predetermined device in each of the one or more communicationmethods.
 18. The relay device according to claim 17, wherein thewireless quality includes received signal strength, a signal to noiseratio, a signal to interference plus noise ratio, reference signalreceived power, or reference signal received quality, in the relaydevice.
 19. The relay device according to claim 14, wherein theinformation indicating the condition regarding the communicationincludes information indicating whether a connection is established withthe predetermined device using each of the one or more communicationmethods.
 20. The relay device according to claim 14, wherein theinformation indicating the condition regarding the communicationincludes information indicating a congestion state of the communicationusing each of the one or more communication methods.
 21. The relaydevice according to claim 14, wherein the one or more communicationmethods include a cellular communication method, a wireless LANcommunication method, or a Bluetooth communication method.
 22. The relaydevice according to claim 14, wherein the relay device is a vehicle. 23.A control method performed by a communication device that performscommunication wirelessly, the control method comprising: transmitting,to one or more other communication devices, a request signal requestinginformation indicating a condition regarding communication between apredetermined device and the other communication devices, in each of oneor more communication methods in the one or more other communicationdevices, the predetermined device being different from the communicationdevice; receiving, from at least any of the one or more othercommunication devices, a response including the information indicatingthe condition regarding the communication in the other communicationdevices; selecting, based on the response received, a device to berequested to transfer the communication of the communication device froma transmission source device of the response, and selecting acommunication method to be used for transferring, in the device; andperforming connection establishment processing including requesting thedevice selected to relay the communication of the communication device,by performing communication between the device and the predetermineddevice using the communication method selected.
 24. A control methodperformed by a relay device that relays communication wirelessly betweena communication device and a predetermined device, the control methodcomprising: receiving, from the communication device, a request signalrequesting information indicating a condition regarding communicationwith the predetermined device in each of one or more communicationmethods in the relay device; and transmitting, to the communicationdevice, a response including the information indicating the conditionregarding the communication in the relay device.
 25. A non-transitorycomputer-readable storage medium that stores a program for causing acomputer included in a communication device that performs communicationwirelessly to: transmit, to one or more other communication devices, arequest signal requesting information indicating a condition regardingcommunication between a predetermined device and the other communicationdevices, in each of one or more communication methods in the one or moreother communication devices, the predetermined device being differentfrom the communication device; receive, from at least any of the one ormore other communication devices, a response including the informationindicating the condition regarding the communication in the othercommunication devices; select, based on the response received, a deviceto be requested to transfer the communication of the communicationdevice from a transmission source device of the response, and select acommunication method to be used for transferring, in the device; andperform connection establishment processing including requesting thedevice selected to relay the communication of the communication device,by performing communication between the device and the predetermineddevice using the communication method selected.
 26. A non-transitorycomputer-readable storage medium that stores a program for causing acomputer included in a relay device that relays communication wirelesslybetween a communication device and a predetermined device to: receive,from the communication device, a request signal requesting informationindicating a condition regarding communication with the predetermineddevice in each of one or more communication methods in the relay device;and transmit, to the communication device, a response including theinformation indicating the condition regarding the communication in therelay device.